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New mods made huge improvement, but still a little off on tuning


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OK so i have a 2008 crf150r and i upgraded with the following parts.  otherwise stock.

 

Carb jetting  45 pilot, 140 main, boyesen QS3 at 1 turn out stock needle and stock clip location, the fuel screw was turned out about a half turn from stock.

 

Boyesen x wing

DRD full exhaust

 

 

It amazing how much better the power band is down low and the mid hit is nasty, top end never seems to fall off, and im over 200lbs!  the sound is awesome!

 

 

here is the problem,  i can only get it to idle about 3-5  seconds and it stalls, it wont start with out a pull of the throttle, and it has a bad bog when hitting the face of a jump in a higher gear, like when i blip it.  that's the only time it will do this, throttle response is lightning fast and no bog when free rev.  takes RPM to get going in first so it wont stall.

 

Ive read about a AP diaphragm grinding mod and a linkage wire, not sure if i need this or not...

 

 

Any help would be appreciated.

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No need to grind the AP diaphragm. Pick up some o-rings (forgot size) and mod the linkage. Takes just a few minutes to do.

 

O-ring mod: https://thumpertalk.com/topic/539540-the-o-ring-mod-for-an-fcr/

 

Recheck the QS/3 after doing the mod. On the QS/3, turning the screw in increases the a/p squirt. You are in the ballpark. I run between 1 turn and 1 1/2 turns out depending on weather and altitude and the pipe I'm running. 
 

Also, as temperature goes down the bike runs leaner. If you are jetted for 40-80 degrees, the Honda jetting chart suggests one size richer main from 0-30 degrees. You are right on the cusp so I wouldn't worry about it.

 

This is a pretty good guide to the FCR:

 

http://www.thumperfaq.com/jetting.htm

Edited by Old Plonker
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Ok so I'll try the oring mod and it sounds like that will fix the bog issue.

How do I get it to idle better. QS3 adjust or fuel screw?

Cold with choke it will start and idle somewhat once it starts and stalls a few times, it will idle for about 10-15 seconds then dies.

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Ok so I'll try the oring mod and it sounds like that will fix the bog issue.

How do I get it to idle better. QS3 adjust or fuel screw?

Cold with choke it will start and idle somewhat once it starts and stalls a few times, it will idle for about 10-15 seconds then dies.

 

Remember that the idle speed on the CRF150R/B is 2,000-2,200 rpm. Set this with the idle speed screw.

 

As Fergus said, fuel screw is for idle and off-idle running, and QS/3 is to fine tune the a/p shot (turn it in to richen the shot, 1/8 turn at a time). I tuned mine to the smallest shot I could get without any bog, but get the pilot setting right first.

 

This post by Eddie Sisneros will help you confirm that you have the appropriate pilot jet and fuel screw setting:

 

https://thumpertalk.com/topic/271735-how-to-confirm-your-pilot-circuit-setting/

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